The present invention relate to an electronic component, and more particularly to a dielectric resonator device, a dielectric filter, a composite dielectric filter, a synthesizer, a distributor, and a communication device including the same, each of which operates in a multimode.
A dielectric resonator in which an electromagnetic wave in a dielectric is repeatedly totally-reflected from the boundary between the dielectric and air to be returned to its original position in phase, whereby resonance occurs is used as a resonator small in size, having a high unloaded Q (Q0). As the mode of the dielectric resonator, a TE mode and a TM mode are known, which are obtained when a dielectric rod with a circular or rectangular cross section is cut to a length of sxc2x7xcexg/2 (xcexg represents a guide wavelength, and s is an integer) of the TE mode or the TM mode propagating in the dielectric rod. When the mode of the cross section is a TM01 mode and the above-described s=1, a TM01xcex4 mode resonator is obtained. When the mode of the cross section is a TE01 mode and s=1, a TE01xcex4 mode dielectric resonator is obtained.
In these dielectric resonators, a columnar TM01xcex4 mode dielectric core or a TE01xcex4 mode dielectric core are arranged in a circular waveguide or rectangular waveguide as a cavity which interrupts the resonance frequency of the dielectric resonator, as shown in FIG. 27.
FIG. 28 illustrates the electromagnetic field distributions of the above-described two modes in the dielectric resonators. Hereupon, a continuous line represents an electric field, and a broken line a magnetic field, respectively.
In the case where a dielectric resonator device having plural stages is formed of dielectric resonators including such dielectric cores, the plural dielectric cores are arranged in a cavity. In the example shown in FIG. 27, the TM01xcex4 mode dielectric cores shown in (A) are arranged in the axial direction, or the TE01xcex4 mode dielectric cores shown in (B) are arranged along the same planed
However, in such a conventional dielectric resonator device, to provide resonators in multi-stages, it is needed to position and fix plural dielectric cores at a high precision. Accordingly, there has been the problem that it is difficult to obtain dielectric resonator devices having characteristics with no variations.
Further, conventionally, TM mode dielectric resonators each having a columnar or cross-shaped dielectric core integrally provided in a cavity have been used. In a dielectric resonator device of this type, the TM modes can be multiplexed in a definite space, and therefore, a miniature, multistage dielectric resonator device can be obtained. However, the concentration of an electromagnetic field energy onto the magnetic cores is low, and a real current flows through a conductor film formed on the cavity. Accordingly, there have been the problem that generally, a high Qo comparable to that of the TE mode dielectric resonator can not be attained.
It is an object of the present invention to provide a multi-mode dielectric resonator device in which dielectric cores can be easily arranged in a cavity, a dielectric resonator device comprising resonators in plural stages can be obtained, and the Q0 is maintained at a high value.
Moreover, it is another object of the present invention to provide a dielectric filter, a composite dielectric filter, a synthesizer, a distributor, and a communication device, each including the above-described multimode dielectric resonator.
In the multimode dielectric resonator device of the present invention, as defined in claim 1, a dielectric core having a substantial parallelepiped-shape, operative to resonate in plural modes is supported substantially in the center of a cavity having a substantial parallelepiped-shape in the state that the dielectric core is separated from the inner walls of the cavity at predetermined intervals, respectively. Since the substantial parallelepiped-shape dielectric core is supported substantially in the center of the cavity having a substantial parallelepiped-shape, as described above, the supporting structure for the dielectric core is simplified. Moreover, since the dielectric core having a substantial parallelepiped-shape, operative to resonate in plural modes is employed, plural resonators can be formed without plural dielectric cores being arranged. A dielectric resonator device having stable characteristics can be formed.
For supporting the dielectric core in the cavity, a support having a lower dielectric constant than the dielectric core is used, as defined in claim 2. Thereby, the concentration of an electromagnetic field energy to the dielectric core is enhanced, and the Q0 can be maintained at a high value.
A supporting portion for the dielectric-core in the cavity may be molded integrally with the dielectric core or cavity, as defined in claim 3. Thereby, the support as an individual part becomes unnecessary. The positional accuracy of the supporting portion with respect the cavity or dielectric core, and moreover, the positioning accuracy of the dielectric core in the cavity are enhanced. Accordingly, a multimode dielectric resonator device having stable characteristics can be inexpensively obtained.
The supporting portion or support, as defined in claim 4, is provided in a ridge portion of the dielectric core or in a portion along a ridge line of the dielectric core, or is provided near to an apex of the dielectric core, as defined in claim 5. Thereby, the mechanical strength of the supporting portion per the overall cross sectional area thereof can be enhanced. Further, in the TM modes, the reduction of the Q0 of the mode where the supporting portion or support is elongated in the vertical direction to the rotation plane of a magnetic field can be inhibited.
The supporting portion or support, as defined in claim 6, is provided in the center of one face of the dielectric core. Thereby, the reduction of the Q0 of a mode different from the TM mode where the supporting portion or support is elongated in the vertical direction to the rotation plane of the magnetic field can be inhibited.
As defined in claim 7, a part of or the whole of the cavity is an angular pipe-shape molded-product, and the dielectric core is supported to the inner walls of the molded product by means of the support or supporting portion. According to this structure, by setting the mold-drafting direction to be coincident with the axial direction of the angular pipe-shape, the cavity and the dielectric core can be easily molded by means of a mold having a simple structure.
Also, according to this invention, formed is a dielectric filter by providing an externally coupling means to couple to a predetermined mode of the multimode dielectric resonator device.
Further, according to this invention, formed is a composite dielectric filter having at least three ports by use of plural above-described dielectric filters.
Further, according to this invention, formed is a synthesizer comprising independently, externally coupling means to couple to plural predetermined modes of the multimode dielectric resonator device, externally, independently, and a commonly externally coupling means to couple to plural predetermined modes of the multimode dielectric resonator device externally commonly, wherein the commonly externally coupling means is an output port, and the plural independently externally coupling means are input ports.
Further, according to this invention, formed is a distributor comprising independently, externally coupling means to couple to predetermined modes of the multimode dielectric resonator device, respectively, independently, and a commonly externally coupling means to couple to plural predetermined modes of the multimode dielectric resonator device commonly, externally, wherein the commonly externally coupling means is an input port, and the plural independently externally coupling means are output ports.
Moreover, according to the present invention, a communication device is formed of the composite dielectric filter, the synthesizer, or the distributor each described above, provided in the high frequency section thereof.